The problem of Phylloxera has been remedied by the present invention. Phylloxera is a louse of the genus Phylloxera that attacks plants by sucking sap and related material from roots, leaves, etc. One type of phylloxera, P. vitifoliae (grape phylloxera), destroys the leaves and roots of grapevines throughout North America and Europe. Historically, Phylloxera has been documented as a major threat to viticulture around the world, having wiped out viticulture in large areas of Europe during the second half of the 19th century.
At the beginning of the 20th century, the German research scientist Carl Borner observed that one type of Vitis cinerea (Vitis cinerea Arnold) was not only tolerant, but actually resistant to phylloxera. Vitis cinerea did not permit the insect to feed on its roots. Unfortunately, Vitis cinerea Arnold has poor rooting and grafting ability. Thus, although genetically superior, Vitis cinerea Arnold never found its place as a rootstock variety.
Yearning for a rootstock variety that has high phylloxera resistance and excellent grafting and rooting ability, Borner conducted a large number of crosses between Vitis cinerea Arnold and other varieties and species. The seedlings were grown in several seedling fields throughout Germany.
In 1936, an initial crossing was conducted at the former "Biologische Reichsanstalt" in Naumburg/Saale during a huge rootstock breeding program that was carried out with the aim of total elimination of Phylloxera. The seedlings which resulted from this breeding program were planted in 1943, by the "Reichsrebenzuchtung" on an examination field in the Zellertal in the Palatinate area, which belonged to the "Landes--Lehr--und Forschungsanstalt Neustadt an der Weinstrasse." Remarkably, the plants survived the Holocaust and World War II.
In 1964, a special selection of the most interesting and most promising new rootstocks derived from the Zellertal were taken to the "Forschungsanstalt Geisenhem/Institut fur Rebenzuchtung." At Geisenheim, Helmut Becker continued Borner's research and examined a range of seedlings more closely. Dr. Ernst Ruhl, as the director at Geisenheim, originally supervised and directed the selection and asexual reproduction of the `Borner`. Dr. Becker was amongst those so directed. The name `Borner` is an attribute to the original sexually reproduced crosses between Vitis cinerea Arnold and other varieties and species, performed by Carl Borner. From the special selection, one new variety was eventually chosen for its strikingly positive viticultural characteristics and its complete phylloxera resistance. The new variety--Selection number Na 5153-54, a cross between Vitis riparia 183 Geisenheim and Vitis cinerea Arnold--proved to combine the complete phylloxera resistance of Vitis cinerea Arnold with the good rooting and grafting ability of Vitis riparia.
Numerous adaptaton, affinity, and resistance tests in various experimental vineyards and under commercial conditions proved positive. Both studies and rootstock trials in several areas under a range of conditions have since shown the positive effect of this rootstock on the performance of the scion and its superiority under high Phylloxera pressure. Thus, the `Borner`variety represents a phylloxera-tolerant rootstock, possessing the ability to retain root system integrity after phylloxera attack, and it has exceptional rooting and grafting ability. variety represents
Several `Borner` motherblocks have been established in Germany, Northern Italy, South France, and Central Portugal. The stock plantations produce propagation material or rootstocks for grafting or any other purpose. Maintenance of the variety is achieved by clonal selection of the original motherplants in combination with negative mass selection in special motherblocks. The variety is maintained by controlled production of pre-base (elite) and base rooted cuttings used for the establishment of new other rootstock propagation plantations for the production of rootstocks for grapevine grafting. Asexual reproduction of the `Borner` is and has always been executed under the strict and accurate control of Ernst Ruhl. Whether asexual reproduction is carried out in Geisenheim's own nursery at Geisenheim/Rheingau, Germany, or in specially selected private nurseries under particular contractual conditions specified for the production of rooted rootstocks, selected and controlled base and pre-base material are always utilized. The `Borner` has displayed stability under asexual reproduction.
In 1989, the `Borner` was registered in the German Variety Registration Office. The National Plant Variety Catalogue of Germany listed the `Borner` with registration number RBU 15. No other synonyms for the `Borner` have been utilized separate from `Borner`, Na 5153-54, and RBU 15. In 1991, the `Borner` was classified in the European Community for all German vine-growing regions. Trials in Italy, Austria, Slovenia, France and other European countries are pending.